Genetic and environmental contributions to alcohol dependence risk in a national twin sample: consistency of findings in women and men

Molecular biology of alcohol dependence, a complex polygenic disorder

Alcohol dependence, and the medical conditions which arise from prolonged excessive alcohol use, have no single cause. Like other complex diseases, they result from a combination of social, personal and genetic contributions; but within any society genetic variation has a substantial influence on individual risk. The genes presently known to affect alcohol dependence produce variation in alcohol metabolism; other genes which affect personality or susceptibility to intoxication are likely to be significant but so far reproducible evidence is scanty. Designs which include related subjects have advantages for the study of complex diseases, because any association effects can be placed in the context of overall heritability and because linkage analysis can also be included. Examples of our studies of alcohol metabolism, consumption and dependence are presented.

The genetics of alcoholism

Recently, the first genome-wide searches for genes predisposing to or protecting against the development of alcohol dependence in humans have been carried out. Genetic studies in animal models of alcohol-related behaviors have also identified candidate chromosomal regions and potential candidate genes that can be tested in human populations.

Statistical methods in genetic research on smoking

A growing body of evidence suggests that genetic factors have an important influence on the onset and course of smoking. Here we review some of the statistical methods that have been used to test for genetic influences on smoking behaviour, with a particular focus on studies of large national twin samples. We show how many of the hypotheses that have been tested using a genetic model-fitting approach have also been reformulated using logistic regression models that will be more familiar to epidemiologists. Such an approach is more easily extended to allow for sociocultural, as well as genetic, influences on smoking behaviour. Using either approach, data are consistent in indicating that certainly in men, and possibly in women, genetic factors play an important role in predicting which individuals who become cigarette smokers progress to being long-term persistent smokers.

Long-term reliability and validity of alcoholism diagnoses and symptoms in a large national telephone interview survey

The long-term reliability and validity of telephone lay interview assessments of alcoholism were examined in the context of a large national community-based survey of over 8,000 male Vietnam era veterans. A subsample of 146 men was interviewed twice by telephone using the same structured interview an average of 15 months apart to evaluate the long-term reliability of alcoholism symptoms and diagnoses. In addition, a search of Department of Veterans Affairs patient treatment files of inpatient hospitalizations between 1970 and 1993 yielded a subsample of 89 interviewed men with a past discharge diagnosis of alcohol dependence. The test-retest reliability of alcohol abuse and alcohol dependence diagnoses was good, with kappa coefficients of 0.74 and 0.61, respectively. The reliability of individual alcoholism symptoms was fair to good, with kappas of 0.46 to 0.67. Ninety-six percent of individuals identified by Department of Veterans Affairs patient treatment files as having an alcohol dependence diagnosis were correctly diagnosed by the telephone interview. The results of the present study provide additional evidence for the long-term reliability and validity of lifetime alcoholism diagnoses, and suggest that the reliability and validity of telephone interview assessments of alcoholism are as good as that of an in-person interview. Telephone administration of structured psychiatric interviews appears to be an attractive alternative to in-person interviewing for gathering information about alcoholism and alcohol-related problems.